The present invention relates to the field of fiber optics and, more specifically, to a fiber-optical connector system.
In the case of fiber-optical connector systems, in which it is usual for two optical fibers to be releasably connected to each other by insertion of two connectors into a coupling from two sides, the end faces of the two fibers to be connected must be brought into contact in such a way that a transfer of the optical signals that is as free as possible from losses can take place between the two fibers. For this purpose, the ends of the optical fibers, which are often adhesively embedded in ferrules, enter from both sides into a guiding sleeve provided in the coupling (see for example FIG. 10 of EP-B1-0 570 652 or FIGS. 20 and 21 of WO-A1-00/16145). In order that this can take place, the ends of the optical fibers or ferrules must be freely accessible at the end of the insertion operation.
On the other hand, it is necessary to prevent the ends of the optical fibers from being soiled when the connectors are not inserted in the coupling. In principle, it is conceivable for this purpose to provide protective caps, which are pushed manually over the free ends of the connectors. In order to avoid incorrect operation, however, a change has taken place in favor of providing the connectors with covering means which open automatically when the connector is inserted into the coupling, and also close again automatically when the connector is pulled out of the coupling. In addition, the coupling means are set up in such a way that a light beam emerging from the free fiber ends is reliably covered and cannot cause any damage.
In WO-A1-00/16145 (ADC) there is a description of a fiber-optical connector system which comprises a connector and a coupling. The connector, in which the optical fiber guided in the interior may optionally be arranged with its end freely accessible (FIGS. 5, 9) or in a ferrule (FIGS. 10, 13), is equipped with a covering flap. The covering flap is mounted pivotably about a fixed pivot axis. It pivots on insertion of the connector into the coupling, when an actuating cam arranged in the coupling comes into engagement with a slotted guideway on the covering flap. The covering flap and its pivoting region are designed in such a way that, after pivoting up, an end portion of the optical fiber or of the ferrule enclosing it projects freely forward out of the connector housing and can enter a sleeve-like guiding part arranged in the coupling. However, this has the consequence that comparatively considerable space is required for accommodating the covering flap on that side toward which the covering flap pivots up. This also applies to a similar known solution with a fixed pivot axis, as disclosed in U.S. Pat. No. 5,379,362.
Another known solution. (EP-B1-0 570 652, Diamond S. A.) provides a covering flap which, when the connector is inserted into the coupling, in a first phase is pivoted up by about 90xc2x0 and in a second, subsequent phase is pushed back rearward parallel to the pivot axis, in order to release completely the end of the ferrule projecting from the connector housing. Although the combined pivoting and pushing movement has the effect that the space requirement for the covering flap is less than in the case of the pure pivoting movement of WO-A1-00/16145, the combined movement represents a comparatively complicated sequence of movements, which requires high precision and is susceptible to malfunctions. In addition, herexe2x80x94as in the case of the solution according to WO-A1-00/16145xe2x80x94the covering flap can be inadvertently opened and remain open even when a connector is not inserted.
A further known solution for a covering or protecting mechanism operating automatically on insertion is described in GB-A-2,112,173 (Thomas and Betts Corp.). In the case of this fiber-optical connector, the fiber lies with its end in a guiding sleeve which projects forward from the connector housing and can be pushed back against the pressure of a spring (44 in FIG. 1 or 144 in FIG. 3), which at the front end has a bore for the fiber. Provided laterally on the outside of the guiding sleeve is a covering in the form of a flexible sheet-metal strip. In the non-inserted state, the covering projects with the front end over the bore in such a way that the bore is closed. When the connector is inserted into a coupling part, the covering is displaced against a spring action (rearward or transversely) in such a way that the bore in the guiding sleeve is released. A disadvantage of this solution is that the guiding sleeve is not protected against mechanical effects when a connector is not inserted. Furthermore, the laterally provided sheet-metal strip prevents the guiding sleeve from being used for centering the connection when the connector is inserted. A force oriented transversely to the direction of insertion is also exerted on the guiding sleeve when the covering is actuated, and can easily lead to malfunctions. In addition, this protective mechanism is not suitable for connectors in which a ceramic ferrule into which the fiber is adhesively embedded by the end is provided instead of the guiding sleeve.
It is therefore the object of the invention to provide a connector system which avoids the disadvantages of known systems and, in particular with a simple and space-saving construction of the covering mechanism, is distinguished by high functional reliability.
The object is achieved by the features of claim 1 in their entirety. The essence of the invention is to divide the covering means into a first covering element, which protects the end of the optical fiber in the axial direction and can be displaced transversely to the axis, and a second covering element, which protects the end of the optical fiber projecting from the housing in the radial direction and can be displaced rearward parallel to the axis, and which has a first passage for the end of the optical fiber, the first passage being able to be closed by the first covering element. The division has the effect of producing simplified movement sequences for the two covering elements. At the same time, the division permits a space-saving arrangement and separate optimization of the functions.
The covering mechanism becomes particularly compact if, according to a first preferred refinement of the invention, the first covering element is arranged displaceably on the second covering element, if the first covering element is formed as a shutter, which is mounted displaceably transversely to the axis in a guideway formed in the second covering element, if, outside the region of the first passage, the guideway bends around in an arc rearward in a direction lying parallel to the axis, and if, for opening and closing the shutter, the shutter is displaced with its rear end parallel to the axis.
The automatic closing of the shutter is preferably brought about by the shutter being biased in the closed direction by a spring element, preferably in the form of a compression spring.
A particularly simple and effective mechanism for opening the shutter is obtained if, according to another preferred refinement of the invention, the shutter is fastened by its rear end to a slide, which is mounted displaceably in the direction of the axis in the housing of the connector, and if engaging means by which the slide is displaced rearward when the connector is inserted into the coupling are provided on the coupling and on the slide. In this case, the engaging means preferably comprise two actuating cams arranged on the inner sides of the side walls of the coupling and also two hook-shaped drivers, which are arranged on the sides of the slide and come into engagement with the actuating cams when the connector is inserted into the coupling.
For reliable prevention of a disturbing reflection of light through the closed shutter back into the optical fiber, it is of advantage if, in the region of the first passage, the guideway runs slightly at an angle to the axis.
The covering mechanism of the invention can be realized particularly simply if the second covering element is formed as a flap-shaped cover, and the guideway for the shutter is formed between the cover and a holder which is provided with a second passage and is fitted into the cover.
For opening the second covering element, in the coupling there is preferably a stop against which the second covering element or the cover butts, and by which the second covering element or the cover is pushed back rearward, thereby releasing the end of the optical fiber, when the connector is inserted into the coupling.
For closing the second covering element, in the coupling and on the second covering element or the cover there are preferably latching means which latch the second covering element or the cover to the coupling when the connector is completely inserted into the coupling, and securely hold the second covering element or the cover in the coupling when the connector is pulled out of the coupling, until the relative displacement between the second covering element or the cover and the housing of the connector causes the end of the optical fiber to be covered again in the radial direction. The latching means preferably comprise a detent provided on the second covering element or cover and also a closure flap, the closure flap being pivotably arranged in the coupling by means of a pivot bearing lying transversely to the axis and closing the coupling when the connector is not inserted, and the closure flap being pivoted up and latching with its free end behind the detent by insertion of the connector into the coupling.